Rolling process

ABSTRACT

A rolling process for the fabrication of rolls in which a roll to be grooved is supported by a backing roll having a soft, resilient, abrasion-resistant outer layer having a range of hardness from about 40 Shore A to about 100 Shore D durometer.

United States Patent Carr et a1. Mar. 11, 1975 1 ROLLING PROCESS {56]References Cited [75] Inventors: George P. Carr, Rochester; James UNITEDSTATES PATENTS A. Mason, Jr., Webster, both of 934,335 9/1909 Nahm eta1. 72/703 N.Y. 1,459,669 6/1923 Berold 1,487,591 3/1924 Na 101/7 [73]Asslgneei Xemx Cwporamn, Stamford, 2,114,072 4/1938 cle v eland 29/l48.4(1099- 2,345,174 4/1944 Malnar 101/7 2,638,050 5/1953 King 29/1484 [22]1973 2,695,857 11/1954 Lewis et a1 721010. 10 [2]] App], No; 425,3753,150,707 9/1964 Howell 72/465 Related Application Data PrimaryExaminerLowell A. Larson [63] Continuation-impart of Ser. No. 266,175,June 26,

1972, abandoned. 57 ABSTRACT A rolling process for the fabrication ofrolls in which a 72/108 f J g Z roll to be grooved is supp rted by abacking r011 having a soft resilient, abrasiomresistam outer layer [58]Field of Search 101/6, 7, 375, 401.1, g a range of hardness from about40 shore A to 72/102, 108, 109, 465, 703, DIG. 14; 29/148.4 D, 132;156/14; 10/107 F about 100 Shore D durometer.

19 Claims, 1 Drawing Figure ROLLING PROCESS This application is acontinuation-in-part of application Ser. No. 266,175 filed June 26,l972, now abandoned.

This invention relates to a rolling process for fabricating groovedrolls.

It is well known that in various metal working operations employingrolls, it is necessary to provide backing rolls. The use of such backingrolls is perhaps best understood with reference to the metal industrywhere they are used generally in combination with work rolls tocounteract detrimental effects the work rolls. Thus, in the case ofvarious roll fabrication techniques, it is desirable to provide backingrolls so that the proper application of force to work rolls will beprovided. The concepts of this invention will be described hereinafterwith respect to metal working; however, it will be understood that theseconcepts are applicable to other materials. Thus, the majorconsiderations involved herein concern the use of backing rolls incombination with impression rolls which in turn engage work rollspassing relative thereto.

ln electrostatic recording as typified by xerography, it is usual toform an electrostatic latent image on an insulating or photoconductiveinsulating surface, generally conforming to information to be recordedor reproduced. This image may then be developed or made visible by theapplication of an electrostatically attractable material which depositsin conformity with the electrostatic latent image to produce a visiblerecord In the usual embodiments of electrostatographic development it isconventional to employ finely divided insulating materials, generallypowders, which are presented to the image bearing surface in particulateform. Thus, conventionally, the electrostatic latent image is generallybeads or granules bearing on their surfaces finely divided pigmentedtoner particles. Alternatively, insulating or conductive toner or liquidink have been presented to the image in an air suspension. Likewise,toner may be carried on the surface ofa brush or brushlike fiber such asa fur brush or a simulated brush of magnetically adhering particles.

As disclosed in U.S. Pat. No. 3,084,043, to Robert Gundlach, anelectrostatic latent image may be devel oped or made visible bypresenting to the image surface a liquid or ink developer on the surfaceofa suitable developer dispensing member. Such developer dispensingmember comprises a support base having disposed on its surface a raisedpattern which may comprise a plurality of fine raised lines, dots, orother raised material. The patterned material on the developerdispensing surface is generally a very finely divided pattern, regularin configuration or at least in pattern size, and adapted to maintainspacing between a developer dispensing surface and a developer receivingsurface sufficient to keep the developer out of contact with therecording surface in the background areas. The developer dispensingmember is prepared for use by an inking process in which ink is suppliedto fill the valleys between the islands or dots ofthe pattern. This maybe accomplished, for example, by wiping the surface with a thoroughlyinked cloth or by means of inking rolls or the like, preferably followedby squeegeeing off the ex cess ink. When prepared in this manner, thedeveloping dispensing member bears on its surface substantially uniformfilm of developer punctured by the dots or other raised pattern in sucha manner that a smooth surface pressed in contact with the developerdispensing member is in contact only with the noninked peaks of thepattern and not with the developer film. Desirably, sufficient inkshould be placed on and allowed to remain on the surface of thedeveloper dispensing member so that this member may be placed against asheet of paper or other relatively smooth surface without transferringquantities of developer to such surface. For image development, thesurface of the developer dispensing member is pressed eithersimultaneously or progressively into the image bearing surface causingdeveloper transfer to the image surface in conformity with theelectrostatic image.

The working surface ofa roll for application of a liquid developer to anelectrically charged photoreceptive surface is composed, for example, ofa multihelicoid thread pattern having from about 150 to about 300threads per inch at about 45 right or left hand lead. Other angles maybe used such as 20 to from axis. The thread configuration is typicallyabout 00055 inch pitch, about 0.001 inch top land, and with about 35 to65 micron depth. The overall roll size may be typically about 1.5 inchin diameter and approximately 9 inches in length, exclusive of journals.Such a roll may be made from aluminum or alloy, or low carbon steel andchromium plated for corrosion and wear protection and is generallyfabricated by mechanical engraving. However, as is obvious to thoseskilled in the art of mechanically engraving such rolls, it is apparentthat such a method of fabrication is very time consuming and inherentlyleads to high costs of manufacture. Using a trihelicoid pattern as anexample, the following would be the basic steps to produce amechanically engraved roll:

I. A master layout of the pattern, opposite hand, many times size, ismade on a polyethylene terephthalate resin material.

2. The master layout is photographically reduced to the proper size,again on a clear polyethylene tercphthalate resin material.

3. The master pattern is transferred to a hardened and ground tool steelmaster engraving cylinder by a photoetching process. Only the patternoutline is transferred, not the pattern depth. W

4. The photo-etched master engraving cylinder is me chanically etched bya master engraving to the desired depth and contour. This step iscritical and requires great skill. The tools and equipment used arerelatively simple and very similar to a jewelers etching equipment.Subsequent engraving success depends almost entirely on the skill of themaster engraver.

5. The master cylinder is then used to make master mills for theengraving of rolls. The process used for making the master mills isbasically the same as used for engraving rolls and is explainedsubsequently in Step 7.

6. A roll blank is machined to tolerance by conventional means. Anextension is left on one end and this is used to drive the roll duringthe mechanical engraving process. After engraving, the extension ismachined off. The roll material is usually AlSl l0l5 or I020 steel.

7. The roll is now ready for engraving. During the engraving process,the roll is placed in a special lathe designed for this purpose. Theroll is placed in the machine with the roll journals supported by bronzeU" shaped bearings. The extension that is left on the roll is engaged ina floating chuck that drives the roll during the engraving process. Themaster engraving mill is mounted in a tool holder directly above theroll. The tool holder rests on the lathe bed and is driven back andforth by a lead screw. The master mill freely floats in the U-shapedbronze bushings in the tool holder and not driven. By means of anadjusting wheel, it is brought in contact with the rotating blank roll,picks up the speed of the blank roll and is driven by frictionalcontact. The advance along the blank roll is controlled by the leadscrew driving the tool holder. The blank roll rotates very slowly,usually no more than rpm. The advance of the master mill along thelength of the blank roll is also very slow, approximately 1 inch over 3minutes for small rolls and considerably slower for larger rolls. Onlarger rolls it is nearly impossible to see the mill advance down theroll as it is moving so slowly. The master mill is rarely bottomed in asingle pass. Usually at least two passes are required on every roll andsometimes considerably more. The amount of infeed per pass is at thediscretion of the operator. During engraving, the roll is continuouslyflooded with lubricant.

8. After engraving, the journal extension is machined off, and the rollis degreased and and given a flash coating of copper.

9. The final step consists of plating with a thin coat of hard chromium.Both plating operations require considerable skill and the usual platingsetup normally would not plate completely and uniformly into suchintricate configurations.

Other roll manufacturing processes have one or more dificiencies. Forexample, milti-die thread cutting has some feasibility for producing amultihelicoid pattern, however, it is very difficult to obtain about a45 lead angle with this process, the maximum lead angle obtainableusually being about 25from the normal to the axis. In producing amultihelicoid pattern on an applicator roll, usually a minimum of 150threads per inch are desirable and about 180 threads per inch arepreferred. With multi-die thread cutting, it is difficult to produce adie of about 180 threads per inch. Further, a special chucking machinethat can feed small rolls at about 0.5 inch per revolution is requiredfor a small roll such as one about one inch in diameter and about 9inches in length. However, even this rate of feed is quite slow andcompounded with the considerable amount of set up time required, thisprocess provides low rates of productivity. Photo engraving/chemicaletching also has some feasibility for producing patterned rolls exceptfor one major drawback. That is, it is very difficult to line up andjoin the ends of the overlay to produce a continuous pattern. A furtherlimitation is that the maximum etched depth obtainable is usually about25j microns. Cylindrical panographic engraving equipment can produce amutlihelicoid pattern, but again the alignment of the thread pattern isa problem the same as occurs in the photoengraving process. Anelectronic automatic cylinder engraving machine may produce about a 180TPI at about a 45 lead angle multihelicoid pattern, or other patterns,on a continuous cylindrical surface. However, since it is a trueengraving process, it is slow and thus costly. Electrochemical grindingis also unsatisfactory for fabricating a roll having about 180 TPIbecause the finest grinding wheel has an individual particle size nearlyas large as the largest thread feature.

Conventional rolling as a method of fabricating rolls differs fromknurling primarily in that in rolling, the roll to be grooved issupported by a backing roll instead of on-end bearings. This allowscenterless supports to be used and makes it possible to increase therate of productivity. An impression tool is pressed against the workroll and allowed to track along the length of the roll to be grooved.The backing roll is conventionally hard steel which compresses anddistorts the newly formed grooves and consequently produces unacceptablerolls, especially when fine patterns such as about TPI or greater are tobe formed. The use of a reverse threaded impression tool avoids thedistortion mentioned above, but produces an unsatisfactory double knurlor diamond pattern which is undesirable for some applications because itdevelops excessively broken line patterns. Further, if soft metalbacking rolls such as copper, brass, aluminum or the like are employed,these backing rolls lack durability and wearing qualities which rapidlylead to distortion resulting in nonuniform dimensions in both thebacking roll and the roll being fabricated. It is also highly desirableto employ a backing roll which is chemically and mechanically stable andcapable of retaining concentricity during use without being susceptibleto the adverse effects of heat, humidity, solvents and abrasion.Obviously, a backing roll susceptible to thermal expansion isundesirable because it may lead to variations in dimensional structureof the roll being fabricated. Also, a metal backing roll susceptible tooxidation effects is undesirable since rusting may occur and result inrust particle removal from the backing roll and cause damage by fallingand embedding in the fabricated rolls. In addition, Coolants andlubricating fluids containing solvents are conventionally employed inroll fabricating processes which further limit the materials that may beemployed as backing rolls due to obvious complications such as chemicalinstability of both the backing roll and the fabricated roll.

Since most roll manufacturing processes are deficient in one or more ofthe above areas, there is a continuing need for an improved method offabrication rolls.

, SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto provide a roll manufacturing process overcoming the above noteddeficiencies.

It is another object of this invention to provide a roll manufacturingprocess which provides dimensional stability to rolls duringfabrication.

It is another object of this invention to provide a roll manufacturingprocess which minimizes damage to fabricated rolls.

It is a further object of this invention to provide a roll manufacturingprocess which is capable of retaining fabricated roll and backing rollconcentricity during use.

Another object of this invention is to provide a roll manufacturingprocess employing a backing roll which is more durable to the action offabricated rolls pressed thereagainst.

It is a further object ofthis invention to provide a roll manufacturingprocess employing a backing roll which is more resilient, wearresistant, and of comparatively low hardness.

it is a further object of this invention to provide a roll manufacturingprocess which is greatly simplified when compared with previously knownprocesses.

It is another object of this invention to provide a roll manufacturingprocess which is significantly less time consuming and costly thanconventional processes.

It is another object of this invention to provide a roll manufacturingprocess which enables higher degree lead angles to be obtained infabricated rolls.

It is another object of this invention to provide a roll manufacturingprocess which enables the fabrication of continuous pattern in workrolls.

It is another object of this invention to provide a roll manufacturingprocess which is superior to known roll manufacturing processes.

The above objects and others are accomplished, generally speaking, byproviding a rolling process for fabricating patterns in cylindricalrolls comprising providing a smooth surfaced cylindrical work roll,impressing a pattern into the cylindrical work roll with an impressiondevice while the work roll is rotated about its axis and supported by asoft, resilient, abrasion resistant, rotating cylindrical backing roll.

In accordance with this invention, any suitable conventional threadrolling machine may be employed in the roll manufacturing process ofthis invention. In the practice of this invention there are employedthree major innovations over the conventional thread rolling machineoperation. The first innovation is that one of the machine dies that is,the conventional backing roll, is replaced with a soft, pliable,resilient elastomer or elastomeric-like backing roll. Secondly, thebacking roll drive is disengaged during the rolling cycle and thebacking roll is allowed to roll freely so as to pick up the speed of thepart being rolled by rolling in contact with it. Since the dies aregenerally independently driven, this obviates the need for perfectsynchronization of driving speeds. Ordinarily, even the slightestvariation in die speeds would cause tearing of the threads on a finepitch such as about 180 TF1. The third innovation is that the die havingan impression tool mounted thereon and the backing roll are brought intoplace to engage and fully grip the work roll before rolling startsinstead of being in motion and at full speed with the work fed intothem, as is the usual case. The relative position of the backing roll tothe work roll is usually so that the axis of the backing roll and thatof the work roll are in line with each other and both may be in ahorizontal plane or a vertical plane. One backing roll is usuallyemployed with a conventional thread rolling machine. however, as isobvious, more than one backing roll may be employed if so desired withdifferent machine designs and such use is intended to be within thescope of this invention.

One ofthe several configurations possible employing the concepts of thisinvention are shown in the drawing. The FIGURE represents an end view ofa roll process fabrication device where a substantially smooth surfacedcylindrical work roll 1 is supported by a soft, resilient, abrasionresistent, freely rotatable substantially cylindrical backing roll 3.Work roll 1 is contacted with a die 2 which is driven by a powermechanism (not shown) so that the work roll 1 is engaged and impressedwith the die pattern while supported by the resilient backing roll 3.

The backing rolls employed in the process of this invention comprise asurface layer of an elastomeric-like or other resilient compositionadhering to a coated or uncoated metal core. Any composition may beemployed as the surface layer for the backing rolls in the rollmanufacturing process of this invention, if the surface layer is softerthan the working roll. Satisfactory compositions are those which arerelatively incompressible at the molding temperatures and pressureshaving a working surface defromable to the shape and texture of thearticle to be fabricated. Suitable compositions include those having arange of hardness from about 40 Shore A to about I00 Shore D durometer.Typical compositions include polyacrylates, polyisobutylenes.polyurethane, polyamides such as, for example. mylon 66, nylon 6, nylon610, nylon 4, nylon l0, nylon ll. nylon l2, and others,fluoroelastomers, chlorosulfonated polyethylene, polyethylene, blockcopolymers of styrene and poly (dimethyl siloxane), natural rubber,polytetrafluoroethylene, polychloroprene, nitrile, polybutadiene,polyisoprene, polysulfide. styrene butadiene, epichlorohydrin silicone,random copolymers of polyethylene and polypropylene with hexadiene, andmixtures thereof.

Substantially incompressible compositions suitable for the manufactureof the backing rolls employed in the roll manufacturing process of thisinvention may consist of a mixture of diisocyanates and polyethers orpolyesters which are mixed together and reacted under controlledconditions. This process forms the prepolymer which is then reacted witha curing agent. The liquid material is then case directly into molds oris processed further for compression, transfer, or injection molding.These materials possess the combined properties of elasticity,stiffness, tear and abrasion resistance suitable for the practice ofthis invention. Either the polyisocyanate, polyester or polyether shouldhave an average number of reactive groups sufficient to provide amoderate degree of branching. For example, we may use a mixture of amoderately branched polyester having about two isocyanate reactiveterminal groups and a diisocyanate. Polyesters having more branchingsuch as those averaging about four hydroxyls per molecule require ahigher proportion of isocyanate to achieve the desired hardness in thebacking rolls. in all cases, the higher the proportion of diisocyanatethat is employed, usually the harder is the cured roll. Conversely,isocyanate to hydroxyl ratios below about one are not often used sincethey generally lead to rolls of undue softness. in accordance withpractice known to those skilled in the art, the polyesters which we mayuse in our invention are dry and free of strong acids which may induceaging of the backing rolls. The diisocyanates which may be employed inthe reaction with the polyester are those which melt above about 150 C.when the diisocyanate is to be added to polyester orpolyester-isocyanate to give the final casting composition. Compositionshaving a hardness of from about to about Shore D durometer, a tensilepsi in the range of about 4,000 to about 7,000, an abrasion loss (mm inthe range of about 25 to about 55, a tear die C PL] in the range ofabout 300 to about 1,200, a tear nicked PL] in the range of about toabout 1,000, a rebound resilience in the range of about 20 percent toabout 45 percent, a specific gravity in the range of about 1.1 to about1.3, elongation in the range of about 250 percent to about l,1l0per-cent, elongation set in the reange of about 2 percent to about 25percent, 300 percent modulus PSl in the range of about 400 to about4,000, 100 percent modulus PS1 in the range of about 200 to about 5,000,and compression set B percent in the range of about 10 to about 40 arepreferred because they provide the use of harder and better wearingmaterials in the backing roll without destroying its resilienc When thesurface layer of the backing roll is a polyurethane, the polyurethanemay be formed by reaction ofa polyethylene glycol, or other polyol, andan isocyanate compound. A polyethylene glycol suitable for use in thisinvention may in general be any of those commercially available with theselection of a particular material being dependent upon the intended useof the backing roll. In general, such compounds are formed by reactingthe ethylene oxide with water, ethylene glycol, or diethylene glycol,and have the general structure configuration: HOCH CH O(CH CHO-),CH CHOH.

Any suitable isocyanate compound may be employed in preparing thepolyurethanes employed in the backing rolls of this invention. Typicalisocyanate compounds include 3,3'-bitolylene-4,4'-diisocyanate,diphenylmethane-4,4'-diisocyanate, 3,3-dimethyldiphenylmethane-4,4'-diisocyanate, metaphenylene diisocyanate,2,4, tolylene diisocyanate dimer, triphenylmethane triisocyanate,hexamethylene diisocyante, dianisidine diisocyanate, polyaryltriisocyanate, and the like.

Any suitable polyol may be employed in preparing the polyurethanesemployed in the backing rolls of this invention. Typical polyols includetrimethylolpropane, 1,4 butanediol, 1,2,6 hexanetriol, sorbitol, aminoalcohol, N,N,N,N-tetrakis(2-hydroxyl propyl) ethylene diamine. diorpolyfunctional silanols based on polydimethyl siloxane and the like.

Any suitable polyamide such as nylon or nylonrelated materials maylikewise be used in the backing rolls of this invention.

Any suitable thickness for the outer surface layer of the backing rollmay be employed in the process of this invention. Preferred thicknessinclude about one to about three inches of outer surface layer on abouta three inch steel core. However, it is quite apparent that thethickness of the outer surface layer of the backing roll may varyaccording to the particular conditions to be encountered in use, and tosome extent, by the size of the roll. Thus, the thickness of the outersurface layer of the backing roll should be sufficient as to preventpossible damage to the threads, patterns or profile of work rolls whenthe work roll is pressed into the backing roll by the impression toolduring fabrication.

Any suitable length for the backing roll may be employed in the processof this invention. Typical lengths include from about one inch to abouttwelve inches. However, when fabricating a grooved aluminum roll ofabout one inch in diameter and about twelve inches in length,satisfactory results are obtained with a backing roll of about twoinches in length.

Any suitable malleable material may be rolled by the process of ourinvention. Typical malleable materials include aluminum alloys, lowcarbon steels, carbon and alloysoft leaded steel, soft stainless steels,brass, copper, and copper base alloys. In general, any material that maybe knurled may be rolled by the process of this invention.

Any suitable impression tool may be employed in the process of thisinvention. Typical impression tools include knurling rolls and the likewhich may be employed to make threads, patterns, profiles, or imprintnumbers on work rolls. However, in the fabrication of rolls to beemployed for application of a liquid developer to an electristaticallycharged photoreceptive surface, an impression tool having a trihelicoidthread pattern of about 180 threads per inch at about a right or lefthand lead, a thread configuration of about 0.0055 inch pitch, about0.001 inch top land, and about a 35 to about 65 micron depth ispreferred because maximum results are obtained in electrostatographicdevelopment.

Any suitable pressure may be applied to the backing rolls employed inthe process of this invention. Typical pressures include about 11,000 toabout 15,000 PS1. However, as is apparent, the pressure employed isdependent to some extent upon the hardness of the work roll and theparituclar pattern or profile to be obtained in the fabricated workroll.

Any suitable fabricated workroll wherein threads knurls, patterns, andthe like are desired may be rolled by the process of this invention.Typical fabricated work rolls include shafts, studs, bolts, pipes,fittings. castings with studs and the like.

In general, the quality of the roll fabricated is dependent on thepressure exerted and the temperature of the backing roll. There may beconsiderable heat generated in the rolling process which in turn mayheat up the backing roll to change its physical properties. Until thebacking roll reaches static conditions, it may be desirable to adjustthe rolling pressure periodically to compensate for these changes andstill make the same quality workpiece. lt has been found that sufficientquality control can be maintained over the rolling process by observingthe rolled parts periodically under a simple microscope. The main pointsto be observed are the thread form and the lack of defects such as tearand burnishing. Periodic examination is desirable to insure that metalchips have not become imbedded in the die or in the backing roll as thismay result in damaged workpieces. Thread depth may be controlled by theuse of a gravure type microscope which measures thread depth directlywhere thread depth is critical.

It has been found that the process of this invention satisfactorilyduplicates the surface produced by mechanical engraving. The productiontime required for producing a satisfactory rolled surface according tothe process of this invention is about fifteen seconds compared withabout forty-five minutes by mechanical engraving, exclusive of loadingand handling time in each case. Fabricated rolls produced according tothe process of this invention may have a greater thread depth thanmechanically engraved rolls, for example, about microns compared withabout 35 microns respectively. This greater thread depth may be thereason why in some instances the rolled rolls fabricated according tothe process of this invention provide developed electrostatic latentimages with less background. Also, this greater thread depth is ofinterest in imaging and coating applications where a greater liquiddeveloper or coating material holding capacity is desirable. Thus, theprocess of this invention is also appropriate for the fabrication ofcoating rollers as well as gravure printing cylinders. In addition, theprocess of this invention is inherently applicable to the production ofregularly spiraled quadragravure or pyrimidal dot patterns.

addition, workpieces such as rolls with a unidirectional helicoid ormultihelicoid groove pattern may be fabricated by the rolling process ofthis invention. Further, the backing roll design prevents damage to theworkpieces being fabricated as they are pressed against the backing rollby the impression tool. The backing rolls of this invention are designedwhereby the backing roll distributes the work load and counteracts theforces from the impression roll in such a manner as to preventdeformation of the profile imposed into the work roll by the impressionroll. The backing roll prevents deformation of the profile of thefabricated work roll while fulfilling the basic function of controllingdeflection.

DESCRIPTION OF PREFERRED EMBODIMENTS The following examples furtherdefine, describe and compare method of utilizing the process of thisinvention of fabricate rolls.

EXAMPLE I A blank roll of 2024-T4 aluminum alloy about one inch indiameter and about nine inches long with the diameter held within atotal tolerance of about 0.0055 inch is inserted in a machine such asavailable from Reed Rolled Thread Die Company, Worcester, Mass, Model8-1 12. The machine is a directly opposing two die straight through oron center thread rolling machine with a capacity of part size from aboutVs inch to about 2 /2 inches in diameter and up to about 24 inches inlength when supported on centers, and up to about feed in length on thrufeed. One of the machine dies is removed and replaced with apolyruethane backing roll (the polyurethane is commercially known asDisogrin, available from Disogrin Industries, Division of PellonCorporation, Manchester, NH.) which is about 3.5 inches in diameter andabout 1.5 inches in length. The polyurethane backing roll has a hardnessof about 80 Shore A durometer and is mounted on a spindle. Thepolyurethane backing roll drive is disengaged. A knurling die about 3.5inches in diameter and about 1.0 inch in length made of hard steel toproduce about a 45 lead angle helix patterned roll containing about 180threads per inch is mounted on a spindle on the other machine head. Thealuminum blank work roll is mounted on centers in the machine and heldby hydraulic pressure. The knurling die and the polyurethane backingroll are brought into place to engage and fully grip the aluminum blankwork roll at a pressure of about l5,000 pounds per square inch beforerolling is started. The machines centers are free floating, withinlimits, in a centering device so that the work roll is always centeredbetween the knurling die and the backing roll during the rollingprocess. The machine is started at a die speed of about I50 rpm and asthe knurling die rotates it pulls the blank roll forward in thecentering device. When the knurling die and backing roll initiallyengage the blank roll and the thread .rolling starts there is someslippage until enough thread form has been generated to pull thecentering device forward. With very fine and shallow thread rolling,there is insufficient strength in the few initial threads to overcomethe resistance of the blank roll holder and these threads tear. Thisresults in about A inch of thread tear on the lead-in end ofthe blankroll. For this reason, the journals are not machined until after thepart has been rolled. As the threads are rolled in the blank roll theybecome the gripping surface pulling the part forward. When the part iscompletely rolled, the machine stops and the knurling die and thebacking roll retract. The centering device pressure is released and thefabricated part is removed from the machine. About thirteen seconds arerequired to groove the blank roll from the time the machine is started.The average thread depth of the grooved roll is about 60 microns.

To determine the quality of the roll fabricated, the grooved surface iscleaned with a solvent to remove any contaminent such as grease and oil.The roll is mounted in a machine suitable for electrostatographic polarliquid development and positioned in contact with a photoreceptorsurface. The photoreceptor is a photosensitive paper composed of anelectroconductive paper substrate and a photoconductive layer thereoverof powdered zinc oxide in an insulating resinous binder. Thephotoreceptor surface is electrostatically charged uniformly by means ofcorona discharge and subjected to imagewise exposure of a light andshadow pattern to form an electrostatic latent image thereon. The latentimage is developed with a polar, conductive homogeneous liquid containedin a trough which is applied to the roll by a feed roller. Excess liquidfrom the roll surface is carefully wiped away at every cycle by adoctoring device. The clean tips of the ridges on the roll provide afinite spacing between the photoconductor and the liquid. The liquid isretained in the grooves of the roll and out of mechanical contact withthe photoconductor surface. Development by electrostatic attractiontakes place on the photoconductor surface in those areas of thephotoconductor containing an electrical charge by the liquid creeping upthe sides of the roll cell walls into contact with the photoconductor.In those areas of the photoconductor which are not electrostaticallycharged, the liquid remains in the roll cell walls out of contact withthe photoreceptor. The printing speed is about 10 inches per second. Theprinted copy produced by the rolled aluminum roll is in general equal toand in some cases superior to that produced by a mechanically engravedlow carbon steel roll which has been chromium plated havingsubstantially the same pattern as the rolled roll and employed as acontrol in that less background is obtained.

EXAMPLE II A blank roll of 2024-T4 aluminum alloy about one inch indiameter and about nine inches in length with the diameter held within atotal tolerance of about 0.0005 inch is inserted in the machinedisclosed as in Example 1. One of the machine dies is removed andreplaced with a polyisoprene backing roll which is about 3.5 inches indiameter and about 1.5 inches in length. The polyisoprene backing rollhas a hardness of about 50 Shore A durometer and is mounted on aspindle. The polyisoprene backing roll drive is disengaged. A knurlingdie as described in Example I is mounted in the machine as in Example I.The aluminum blank roll is mounted in the machine as in Example I. Therolling process of Example I is followed. About thirteen seconds arerequired to groove the blank roll from the time the machine is started.The average thread depth of the grooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled aluminum roll is in general equal toand in some cases superior to that produced by a mechanically engravedroll as described in Example I and employed as a control in that lessbackground is obtained.

EXAMPLE Ill A blank roll of 606l-TG aluminum alloy about one inch indiameter and about nine inches long with the diameter held within atotal tolerance of about 0.0005 inch is inserted in the machinedisclosed as in Example I. One of the machine dies is removed andreplaced with a polyurethane backing roll which is about 3.5 inches indiameter and about 1.5 inches in length. The polyurethane backing rollhas a hardness of about 80 Shore A durometer and is mounted on aspindle. The polyurethane backing roll drive is disengaged. A knurlingdie as described in Example I is mounted in the machine as in Example I.The aluminum blank roll is mounted in the machine as in Example I. Therolling process of Example I is followed. About thirteen seconds arerequired to groove the blank roll from the time the machine is started.The average thread depth of the grooved roll is about 55 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled aluminum roll is in general equal toand in some cases superior to that produced by a mechanically engravedroll as described in Example I and employed as a control in that lessbackground is obtained.

EXAMPLE lV A blank roll of 606l-TG aluminum alloy about one inch indiameter and about nine inches long with the diameter held within atotal tolerance of about 0.0005 inch is inserted in the machinedisclosed as in Example I. One of the machine dies is removed andreplaced with a polyisoprene backing roll which is about 3.5 inches indiameter and about 1.5 inches in length. The polyisoprene backing rollhas a hardness of about 50 Shore A durometer and is mounted on aspindle. The' poly-isoprene backing roll drive is disengaged. A knurlingdie as described in Example I is mounted in the machine as in Example I.The aluminum blank roll is mounted in the machine as in Example I. Therolling process of Example I is followed. About thirteen sec- EXAM PLE VA blank roll of 2024-T4 aluminum alloy about one inch in diameter andabout nine inches long with the diameter held within a total toleranceof about 0.0005 inch is inserted in the machine disclosed as inExample 1. One of the machine dies is removed and replaced with apolyurethane backing roll which is about 3.5

inches in diameter and about 1.5 inches in length. The polyurethanebacking roll has a hardness of about Shore D durometer and is mounted ona spindle. The polyurethane backing roll drive is disengaged. A knurlingdie as described in Example I is mounted in the machine as in Example I.The aluminum blank roll is mounted in the machine as in Example I. Therolling process of Example I is followed. About thirteen seconds arerequired to groove the blank roll from the time the machine is started.The average thread depth of the grooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled aluminum roll is in general equal toand in some cases superior to that produced by a mechanically engravedroll as described in Example I and employed as a control in that lessbackground is obtained.

EXAMPLE VI A blank roll of 606l-TG aluminum alloy about one inch indiameter and about nine inches long with the diameter held with a totaltolerance of about 0.0005 inch is inserted in the machine disclosed asin Example I. One of the machine dies is removed and replaced with apolyurethane backing roll which is about 3.5 inches in diameter andabout 1.5 inches in length. The polyurethane backing roll has a hardnessof about Shore D durometer and is mounted on a spindle. The polyurethanebacking roll drive is disengaged. A knurling die as described inExample] I is mounted in the machine as in Example I. The aluminum blankroll is mounted in the machine as in Example I. The rolling process ofExample I is followed. About 13 seconds are required to groove the blankroll from the time the machine is started. The average thread depth ofthe grooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled aluminum roll is in general equal toand in some cases superior to that produced by a mechanically engravedroll as described in Example I and employed as a control in that lessbackground is obtained.

EXAMPLE Vll A blank roll of mild steel about one inch in diameter andabout nine inches long with the diameter held within a total toleranceof about 0.0005 inch is inserted in the machine disclosed as in ExampleI. One of the machine dies is removed and replaced with a polyurethanebacking roll which is about 3.5 inches in diameter and about 1.5 inchesin length. The polyurethane backing roll has a hardness of about Shore Ddurometer and is mounted on a spindle. The polyurethane backing rolldrive is disengaged. A knurling die as described in Example l is mountedin the machine as in Example I. The mild steel blank roll is mounted inthe machine as in Example I. The rolling process of Example l isfollowed. About fifteen seconds are required to groove the blank rollfrom the time the machine is started. The average thread depth of thegrooved roll is about 55 microns.

Copy quality evaluation of the grooved roll is done as I in Example I.The printed copy produced by the rolled mild steel roll is in generalequal to and in some cases superior to that produced by a mechanicallyengraved roll as described in Example I and employed as a control inthat less background is obtained.

EXAMPLE VIII A blank roll of mold steel about one inch in diameter andabout nine inches long with the. diameter held within a total toleranceof about 0.0005 inch is inserted in the machine disclosed as in ExampleI. One of the machine dies is removed and replaced with a polyisoprenebacking roll which is about 3.5 inches in diameter and about 1.5 inchesin length. The polyisoprene backing roll has a hardness of about 40Shore A durometer and is mounted on a spindle. The polyisoprene backingroll drive is disengaged. A knurling die as described in Example I ismounted in the machine as in Example I. The mild steel blank roll ismounted in the machine as in Example I. The rolling process of Example Iis followed. About 15 seconds are required to groove the blank roll fromthe time the machine is started. The average thread depth of the groovedroll is about 55 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled mild steel roll is in general equalto and in some cases superior to that produced by a mechanicallyengraved roll as described in Example I and employed as a control inthat less background is obtained.

EXAMPLE IX A blank roll of copper about 1 inch in diameter and aboutnine inches'long with the diameter held within a total tolerance ofabout 0.0005 inch is inserted in the machine disclosed as in Example I.One of the machine dies is removed and replaced with a polybutadienebacking roll which is about 3.5 inches in diameter and about 1.5 inchesin length. The polybutadiene backing roll has a hardness of about 70Shore Ddurometer and is mounted on a spindle. The polybutadiene backingroll drive is disengaged. A knurling die as described in Example I ismounted in the machine as in Example I. The copper blank roll is mountedin the machine as in Example I. The rolling process of Exampel I isfollowed. About thirteen seconds are required to groove the blank rollfrom the time the machine is started. The average thread depth of thegrooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled copper roll is in general equal toand in some cases superior to that produced by a mechanically engravedroll as described in Example I and employed as a control in that lessbackground is obtained.

EXAMPLE X A blank roll of copper about one inch in diameter and aboutnine inches long with the diameter held within a total tolerance ofabout 0.0005 inch in inserted in the machine disclosed as in Example I.One of the machine dies is removed and replaced with a polyurethanebacking roll which is about 3.5 inches in diameter and about 1.5 inchesin length. The polyurethane backing roll has a hardness ofabout 80 ShoreA durometer and is mounted on a spindle. The polyurethane backing rolldrive is disengaged. A knurling die as described in Example I is mountedin the machine as in Example I. The copper blank roll is mounted in themachine as in Example I. The rolling process of Example l is followed.About 13 seconds are required to groove the blank roll from the time themachine is started. The

average thread depth of the grooved roll is about 60 microns.

Copy quality evaluation of the grooved roll is done as in Example I. Theprinted copy produced by the rolled copper roll is in general equal toand in some cases superior to that produced by a mechanically engravedroll as described in Example I and employed as a control in that lessbackground is obtained.

Although specific materials and conditions are set forth in theforegoing examples, these are merely intended as illustrations of thepresent invention. Various other suitable roll materials such as thoselisted above may be substituted for those in the examples with similarresults. Other materials may also be added to the backing roll materialsto sensitize, synergize or otherwise improve the fabricating propertiesor desirable properties of the process. Any system which impartsstresses to work rolls which may be counteracted by the backing rollsemployed in the process of this invention is contemplated by thisdisclosure.

Other modifications of the present invention will occur to those skilledin the art upon a reading of the present disclosure. These are intendedto be included within the scope of this invention.

What is claimed is:

1. A rolling process for fabricating patterns in cylindrical rollscomprising providing a substantially smooth surfaced cylindrical workroll, impressing a pattern into said cylindrical work roll with animpression device while said cylindrical work roll is rotated about itsaxis and supported by a soft, resilient, abrasion resistant. freelyrotatably substantially cylindrical backing roll.

2. A rolling process according to claim 1 wherein said cylindrical workroll is rotated about its axis and supported by said cylindrical backingroll mounted on a thread rolling machine having at least twoindependently driven dies.

3. A rolling process according to claim 2 including replacing one ofsaid dies with said cylindrical backing rolls.

4. A rolling process according to claim 3 including disengaging thedrive of said cylindrical backing roll.

5. A rolling process according to claim 4 including bringing saidcylindrical backing roll and said impression device into contact withsaid cylindrical work roll before rolling starts.

6. A rolling process according to claim 1 wherein said cylindricalbacking roll comprises a surface layer of a soft, resilient, abrasionresistant composition adhering to a metal core.

7. A rolling process according to claim 6 wherein said composition has ahardness from about 40 Shore A to about 100 Shore D durometer.

8. A rolling process according to claim 6 wherein said composition has ahardness from about to about Shore D durometer.

9. A rolling process according to claim 6 wherein said composition isselected from the group consisting of polyurethane polyisoprene,polybutadiene and nylon.

10. A rolling process according to claim 6 wherein said cylindricalbacking roll comprises from about one to about three inches of saidsurface layer of said composition adhering to said metal core.

11. A rolling process according to claim 1 wherein said impressiondevice comprises a trihelicoid thread pattern from about to about 240threads per inch at about a 45 lead, a thread configuration of about0.005 inch pitch, about 0.001 inch top land, and about a 35 to about 65micron depth.

12. A rolling process according to claim 1 including impressing saidpattern into said cylindrical work roll with said impression device at apressure of from about 11,000 to about l5,000 pounds per square inchwhile said cylindrical work roll is rotated about its axis and supportedby said rotating cylindrical backing roll.

13. A rolling process according to claim 12 wherein said cylindricalbacking roll counteracts said pressure to prevent deformation of saidpattern impressed into said cylindrical work roll with said impressiondevice.

14. A rolling process according to claim 1 wherein said cylindrical workroll is about one inch in diameter and about nien inches in length.

15. A rolling process according to claim 14 wherein said cylindricalwork roll comprises an aluminum roll.

16. A rolling process according to claim 14 wherein said cylindricalwork roll comprises a copper roll.

17. A rolling process according to claim 14 wherein said cylindricalwork roll comprises a mild steel roll.

18. A rolling process according to claim 1 including impressing saidpattern into said cylindrical work roll with said impression device at aspeed ofabout revolutions per minute while said cylindrical work roll isrotated about its axis and supported by said cylindrical backing roll.

19. A rolling process according to claim 1 including impressing saidpattern into said cylindrical work roll with said impression device inabout thirteen seconds while said cylindrical work roll is rotated aboutits axis and supported by said cylindrical backing roll.

1. A rolling process for fabricating patterns in cylindrical rollscomprising providing a substantially smooth surfaced cylindrical workroll, impressing a pattern into said cylindrical work roll with animpression device while said cylindrical work roll is rotated about itsaxis and supported by a soft, resilient, abrasion resistant, freelyrotatably substantially cylindrical backing roll.
 1. A rolling processfor fabricating patterns in cylindrical rolls comprising providing asubstantially smooth surfaced cylindrical work roll, impressing apattern into said cylindrical work roll with an impression device whilesaid cylindrical work roll is rotated about its axis and supported by asoft, resilient, abrasion resistant, freely rotatably substantiallycylindrical backing roll.
 2. A rolling process according to claim 1wherein said cylindrical work roll is rotated about its axis andsupported by said cylindrical backing roll mounted on a thread rollingmachine having at least two independently driven dies.
 3. A rollingprocess according to claim 2 including replacing one of said dies withsaid cylindrical backing rolls.
 4. A rolling process according to claim3 including disengaging the drive of said cylindrical backing roll.
 5. Arolling process according to claim 4 including bringing said cylindricalbacking roll and said impression device into contact with saidcylindrical work roll before rolling starts.
 6. A rolling processaccording to claim 1 wherein said cylindrical backing roll comprises asurface layer of a soft, resilient, abrasion resistant compositionadhering to a metal core.
 7. A rolling process according to claim 6wherein said composition has a hardness from about 40 Shore A to about100 Shore D durometer.
 8. A rolling process according to claim 6 whereinsaid composition has a hardness from about 70 to about 95 Shore Ddurometer.
 9. A rolling process according to claim 6 wherein saidcomposition is selected from the group consisting of polyurethanepolyisoprene, polybutadiene and nylon.
 10. A rolling process accordingto claim 6 wherein said cylindrical backing roll comprises from aboutone to about three inches of said surface layer of said compositionadhering to said metal core.
 11. A rolling process according to claim 1wherein said impression device comprises a trihelicoid thread patternfrom about 180 to about 240 threads per inch at about a 45* lead, athread configuration of about 0.005 inch pitch, about 0.001 inch topland, and about a 35 to about 65 micron depth.
 12. A rolling processaccording to claim 1 including impressing said pattern into saidcylindrical work roll with said impression device at a pressure of fromabout 11,000 to about 15,000 pounds per square inch while saidcylindrical work roll is rotated about its axis and supported by saidrotating cylindrical backing roll.
 13. A rolling process according toclaim 12 wherein said cylindrical backing roll counteracts said pressureto prevent deformation of said pattern impressed into said cylindricalwork roll with said impression device.
 14. A rolling process accordingto claim 1 wherein said cylindrical work roll is about one inch indiameter and about nien inches in length.
 15. A rolling processaccording to claim 14 wherein said cylindrical work roll comprises analuminum roll.
 16. A rolling process according to claim 14 wherein saidcylindrical work roll comprises a copper roll.
 17. A rolling processaccording to claim 14 wherein said cylindrical work roll comprises amild steel roll.
 18. A rolling process according to claim 1 includingimpressing said pattern into said cylindrical work roll with saidimpression device at a speed of about 150 revolutions per minute whilesaid cylindrical work roll is rotated about its axis and supported bysaid cylindrical backing roll.